Polyimide precursor, polyimide precursor composition, polyimide film, method for producing same, and use thereof

Abstract

To provide a polyimide precursor and a polyimide precursor solution for providing a polyimide film excellent in heat resistance and significantly improved in physical properties such as the transparency, the yellow index, and Young's modulus.SOLUTION: A polyimide precursor comprises a structural unit derived from an acid dianhydride and a structural unit derived from a diamine compound represented by the chemical formula. In the formula, A is O or S; R1 and R2 are each independently halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12) aryl; and m and n are each independently an integer from 0 to 3.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyimide precursor, a polyimide precursor solution, a polyimide film, a method for producing the same, and uses thereof. [Background technology]

[0002] Polyimides have been attracting attention as a lightweight, flexible material with high heat resistance. In this field, aromatic polyimides have attracted attention as resins with excellent thermal dimensional stability. Polyimide films, which are molded products made from aromatic polyimides with a rigid, linear chemical structure, are widely used in fields requiring high thermal dimensional stability (low linear thermal expansion coefficient), such as base films for flexible substrates and interlayer insulating films for semiconductors. However, aromatic polyimides with low linear thermal expansion coefficients are strongly colored due to the interaction of intramolecular conjugation and intramolecular and intermolecular charge transfer, making them difficult to apply to optical applications. Furthermore, polyimides have the disadvantage of poor processability due to their very strong intermolecular forces.

[0003] Flexible devices are manufactured by coating a polyimide precursor composition on a carrier substrate, curing it to form a film, completing the device through subsequent processes such as thin film transistor (TFT) and organic film deposition, and then detaching the completed device from the carrier substrate. Flexible devices, which require high-temperature processes, require heat resistance at high temperatures. In particular, when using a thin film transistor process using low-temperature polysilicon (LTPS), the process temperature can approach 500°C. Therefore, the polyimide film formed on the carrier substrate must be heat-resistant and not undergo thermal decomposition due to hydrolysis during high-temperature processes. Furthermore, the film must have not only storage stability but also transparency after processing.

[0004] Therefore, for the production of flexible devices, it is necessary to develop new polyimides that satisfy high heat resistance, are hydrolysis-resistant, exhibit excellent chemical resistance and storage stability, and can improve optical and mechanical properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Publication No. 2019-0153225 (May 23, 2019) Summary of the Invention [Problem to be solved by the invention]

[0006] One aspect of the present invention provides a polyimide precursor and a polyimide precursor solution for producing a polyimide film having excellent heat resistance and significantly improved physical properties such as transparency, yellowness index, and Young's modulus.

[0007] Another aspect provides a polyimide film using the polyimide precursor solution and a method for producing the same. Another aspect provides a multilayer structure and a photoelectric device including the polyimide film. [Means for solving the problem]

[0008] According to one embodiment, there is provided a polyimide precursor including a structural unit derived from a diamine compound represented by the following Chemical Formula 1 and a structural unit derived from an acid dianhydride.

[0009] [Chemical formula 1] [ka]

[0010] (In the above Chemical Formula 1, A is O or S; R 1and R 2 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; m and n are each independently an integer of 0 to 3.

[0011] In the chemical formula 1 according to one embodiment of the present invention, R 1 and R 2 are, independently of each other, halogen, (C1-C10) alkyl, or halo(C1-C10) alkyl; n and m may, independently of each other, be integers from 0 to 1.

[0012] Chemical Formula 1 according to one embodiment of the present invention may be represented by Chemical Formula 2 below.

[0013] [Chemical formula 2] [ka]

[0014] (In the above Chemical Formula 2, R 1 and R 2 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; m and n are each independently an integer of 0 to 3.

[0015] In the chemical formula 2 according to one embodiment of the present invention, R 1 and R 2 are, independently of each other, halogen, (C1-C5) alkyl, or halo(C1-C5) alkyl; n and m may, independently of each other, be integers from 0 to 1.

[0016] The acid dianhydride according to one embodiment of the present invention may be represented by the following Chemical Formula 3:

[0017] [Chemical formula 3] [ka]

[0018] (In the above Chemical Formula 3, R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; p is an integer from 0 to 2.

[0019] The polyimide precursor according to one embodiment of the present invention may further include a structural unit derived from a diamine compound represented by the following Chemical Formula 4:

[0020] [Chemical formula 4] [ka]

[0021] (In the above Chemical Formula 4, R 3 and R 4 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 5 is hydrogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; s and t are integers from 0 to 3.

[0022] Specifically, the polyimide precursor according to one embodiment of the present invention may include a repeating unit represented by the following Chemical Formula 11:

[0023] [Chemical formula 11] [ka]

[0024] (In the above Chemical Formula 11, A is O or S; R 1 and R 2are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; R a and R b are, independently of each other, hydrogen or (C1-C10) alkyl; m and n are, independently of each other, integers from 0 to 3; p is an integer from 0 to 2.

[0025] A polyimide precursor according to one embodiment of the present invention may contain the repeating unit represented by Chemical Formula 11 in an amount of 10 to 100 mol %.

[0026] According to another aspect, there is provided a polyimide precursor solution comprising the polyimide precursor and a solvent. The solvent according to one embodiment of the present invention may be an amide, such as N,N-diethylacetamide, N,N-diethylformamide, N-ethylpyrrolidone, N,N-dimethylpropionamide, N,N-diethylpropionamide, or a mixture thereof.

[0027] According to another embodiment, there is provided a polyimide film comprising a repeating unit represented by the following Chemical Formula 12:

[0028] [Chemical formula 12] [ka]

[0029] (In the above chemical formula 12, A is O or S; R 1 and R 2 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; m and n are, independently of each other, integers from 0 to 2; p is an integer from 0 to 2.

[0030] The polyimide film according to an embodiment of the present invention may further include a repeating unit represented by the following Chemical Formula 13:

[0031] [Chemical formula 13] [ka]

[0032] (In the above Chemical Formula 13, R 3 and R 4 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 5 is hydrogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; s and t are integers from 0 to 3; p is an integer from 0 to 2.

[0033] The polyimide film according to one embodiment of the present invention may have a coefficient of thermal expansion (CTE) of more than 0 and not more than 20 ppm / °C at 100 to 450°C, and may have a yellowness index (YI) according to ASTM E313 of less than 25 and a Young's modulus according to ASTM D882 of more than 7.0, for example.

[0034] The polyimide film according to one embodiment of the present invention may be used for a device substrate, a display substrate, an optical film, an IC package, an electrodeposited film, a multilayer FRC, a tape, a touch panel, or a protective film for an optical disk.

[0035] According to still another aspect, there is provided a laminate and a photoelectric device including the polyimide film. According to yet another aspect, there is provided a method for producing a polyimide film, comprising the steps of applying the polyimide precursor solution to a substrate and then heat treating the substrate.

[0036] In the method for producing a polyimide film according to one embodiment of the present invention, the heat treatment is a first heat treatment step carried out at a temperature below 100°C; a second heat treatment step carried out at a temperature greater than 100°C and less than or equal to 300°C; and a third heat treatment step carried out at a temperature above 300°C and not exceeding 500°C.

[0037] Furthermore, the polyimide precursor solution according to one embodiment of the present invention may contain 10 to 13 wt % of solid content based on the total weight. [Effects of the Invention]

[0038] A polyimide precursor according to one embodiment of the present invention employs a diamine compound having a specific structure, and a polyimide film produced using the polyimide precursor has significantly improved thermal expansion coefficient, transparency, and heat resistance, as well as excellent yellowness index, breaking strength, and Young's modulus.

[0039] Furthermore, a polyimide film prepared using a polyimide precursor solution containing a polyimide precursor according to an embodiment of the present invention has excellent thermal expansion coefficient and residual stress, since stress in the substrate does not increase even during high-temperature heat treatment, and does not suffer from problems such as bending, peeling, and breakage. Therefore, the polyimide film according to one embodiment of the present invention has excellent optical properties due to the reduced optical anisotropy, and can achieve uniform transmittance and excellent transparency.

[0040] In addition, the polyimide film prepared from the polyimide precursor solution according to one embodiment of the present invention is colorless and transparent, and has excellent heat resistance, mechanical strength, flexibility, etc., and can be very usefully used in various fields such as device substrates, flexible display substrates, optical films, IC (integrated circuit) packages, electrodeposited films (adhesive films), multilayer FPCs (flexible printed circuits), tapes, touch panels, and protective films for optical disks. DETAILED DESCRIPTION OF THE INVENTION

[0041] Unless otherwise defined, all technical and scientific terms in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The terms used in the description of the present invention are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0042] Furthermore, units used in this specification unless otherwise specified are based on weight, and for example, units such as % or ratio mean % by weight or weight ratio, and unless otherwise defined, % by weight means the weight percentage of any one component of the total composition.

[0043] In addition, the numerical ranges used herein include the lower and upper limits, all values ​​within the range, increments logically derived in the form and width of the defined range, all values ​​defined therein, and all possible combinations of upper and lower limits of numerical ranges defined in different forms. Unless otherwise specified in the specification of the present invention, values ​​outside the numerical range that may occur due to experimental error or rounding off of values ​​are also included in the defined numerical range.

[0044] As used herein, the term "comprising" is an open-ended term having the same meaning as terms such as "comprising," "containing," "having," or "characterized by," and does not exclude additional, unrecited elements, materials, or steps.

[0045] The term "polyimide precursor solution" as used herein refers to a composition for producing a polyimide, and specifically, the polyimide precursor may have the same meaning as polyamic acid. The polyimide precursor solution may also be used as a composition for producing a polyamideimide.

[0046] The term "polyimide film" as used herein refers to a molded product of polyimide derived from a polyimide precursor solution, and may have an equivalent meaning to polyimide. As used herein, the term "halogen" refers to a fluorine (F), chlorine (Cl), bromine (Br), or iodine (I) atom.

[0047] As used herein, the term "alkyl" refers to an organic radical derived from an aliphatic hydrocarbon by the removal of one hydrogen and includes both straight-chain and branched forms. As used herein, the term "alkoxy" refers to *-O-alkyl, wherein alkyl is as defined above. As used herein, the term "haloalkyl" refers to an alkyl group as defined above in which one hydrogen has been replaced with a halogen.

[0048] As used herein, the term "aryl" refers to an organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, and includes single or fused ring systems suitably containing 4 to 7, preferably 5 or 6, ring atoms in each ring, and includes multiple aryls linked by a single bond. Examples include, but are not limited to, phenyl, naphthyl, biphenyl, terphenyl, and the like.

[0049] A polyimide precursor according to one embodiment includes structural units derived from a novel diamine compound having a specific structure and structural units derived from an acid dianhydride compound. The novel diamine compound is represented by the following chemical formula 1:

[0050] [Chemical formula 1] [ka]

[0051] (In the above Chemical Formula 1, A is O or S; R 1 and R 2 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; m and n are each independently an integer of 0 to 3.

[0052] The polyimide precursor employs a diamine compound containing a benzothiazolyl group or a benzoxazolyl group as a polyimide monomer, thereby imparting linearity and rigidity to the polyimide precursor, thereby imparting significantly improved optical and mechanical properties, such as high heat resistance with an excellent thermal expansion coefficient, chemical resistance, and transparency.

[0053] In order to produce a polyimide film having excellent optical and mechanical properties, R 1 and R 2 are, independently of each other, halogen, (C1-C10) alkyl, or halo(C1-C10) alkyl; n and m may, independently of each other, be integers from 0 to 1.

[0054] In one embodiment of the present invention, R 1 and R 2are, independently of each other, halogen, (C1-C5) alkyl, or halo(C1-C5) alkyl; n and m may, independently of each other, be integers from 0 to 1.

[0055] In one embodiment of the present invention, the formula 1 may be represented by the following formula 1-1:

[0056] [Chemical formula 1-1] [ka]

[0057] (In the above chemical formula 1-1, A is O or S; R 1 and R 2 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; m and n are each independently an integer of 0 to 3.

[0058] As an example, in Formula 1-1, A is O or S; R 1 and R 2 are, independently of each other, halogen, (C1-C5) alkyl, halo(C1-C5) alkyl, (C1-C5) alkoxy, or (C6-C12) aryl; m and n may, independently of each other, be integers from 0 to 1, specifically, A is O or S; R 1 and R 2 are, independently of each other, halogen, (C1-C5) alkyl, or halo(C1-C5) alkyl; m and n may, independently of each other, be integers from 0 to 1, more specifically, A is O; R 1 and R 2 are, independently from each other, halogen, (C1-C5)alkyl, halo(C1-C5)alkyl, (C1-C5)alkoxy, or (C6-C12)aryl; m and n may be 0.

[0059] In one embodiment of the present invention, the novel diamine compound contains the above-described benzothiazolyl group or benzoxazolyl group, and also has a specific substituent, CF, at a specific position, thereby enabling the production of a polyimide film with improved physical properties, particularly higher transparency.

[0060] In one embodiment of the present invention, the above-mentioned Chemical Formula 1 may be represented by the following Chemical Formula 2:

[0061] [Chemical formula 2] [ka]

[0062] (In the above Chemical Formula 2, R 1 and R 2 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; m and n are each independently an integer of 0 to 3.

[0063] In one embodiment of the present invention, the diamine compound represented by Chemical Formula 2 is a compound in which a benzoxazole having an amino group, a specific substituent CF3 introduced at a specific position, and a benzene having an amino group are linked by a single bond. By including a structural unit derived from the diamine compound represented by Chemical Formula 2, a polyimide film having an excellent thermal expansion coefficient and excellent transparency due to low yellowness can be realized.

[0064] In the chemical formula 2 according to one embodiment of the present invention, R 1 and R 2 are, independently of each other, halogen, (C1-C5) alkyl, or halo(C1-C5) alkyl; n and m may, independently of each other, be an integer from 0 to 1, preferably R 1 and R 2are, independently from each other, halogen, (C1-C5) alkyl, or halo(C1-C5) alkyl; n and m may be 0.

[0065] Specifically, in one embodiment of the present invention, the diamine compound may be selected from the following compounds, but is not limited thereto.

[0066] [ka] [ka] [ka] [ka] [ka] [ka]

[0067] For example, in the above-mentioned Chemical Formula 3, R 11 is (C1-C5) alkyl, or halo(C1-C5) alkyl; p may be an integer from 0 to 1, more preferably R 11 is (C1-C5) alkyl, or halo(C1-C5) alkyl; p may be 0.

[0068] A polyimide precursor according to an embodiment of the present invention may further include a structural unit derived from a diamine compound in addition to the structural unit derived from the diamine compound represented by Chemical Formula 1. Examples of the further included diamine compound include 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-oxydianiline, 3,3'-oxydianiline, 3,4'-oxydianiline, 4,4'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 4,4'-diaminodiphenyl N-methylamine, 4,4'-diaminodiphenyl N-phenylamine, 1,4-diaminobenzene (p-phenylenediamine), biphenyl, phenylamine ... Examples of the bis(4-aminophenoxy)phenyl include bis{4-(4-aminophenoxy)phenyl}sulfone, bis{4-(3-aminophenoxy)phenyl}sulfone, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, and 2,2-bis(4-aminophenoxyphenyl)propane, which may be used alone or in combination.

[0069] The polyimide precursor according to one embodiment of the present invention may further include a structural unit derived from a diamine compound represented by the following Chemical Formula 4:

[0070] [Chemical formula 4] [ka]

[0071] (In the above Chemical Formula 4, R 3 and R 4are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 5 is hydrogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; s and t are integers from 0 to 3.

[0072] The polyimide precursor according to one embodiment of the present invention further includes a structural unit derived from the diamine compound represented by Chemical Formula 4, thereby enabling the production of a polyimide film having not only better optical and mechanical properties but also more controlled physical properties.

[0073] In the chemical formula 4 according to one embodiment of the present invention, R 3 and R 4 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 may be hydrogen or (C1-C10) alkyl, and s and t may be integers from 0 to 1, specifically, R 3 and R 4 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 may be hydrogen or (C1-C5) alkyl, and s and t may be integers from 0 to 1, more specifically, s and t may be 0.

[0074] The polyimide precursor according to one embodiment of the present invention may further include a structural unit derived from a diamine compound represented by the following Chemical Formula 5:

[0075] [Chemical formula 5] [ka]

[0076] (In the above Chemical Formula 5, R 6 and R 7 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; a and b are each independently an integer of 0 to 3.

[0077] For example, in the above-mentioned Chemical Formula 5, R 6 and R 7 are, independently of each other, halogen, (C1-C10) alkyl, or halo(C1-C10) alkyl; a and b may, independently of each other, be integers from 0 to 1, more specifically, a and b may be 0.

[0078] In one embodiment of the present invention, the acid dianhydride may be any compound having an acid dianhydride functional group, and specifically may be a tetracarboxylic acid dianhydride. The tetracarboxylic acid dianhydride may be a compound selected from a (C8-C36) aromatic tetracarboxylic acid dianhydride, a (C6-C36) aliphatic tetracarboxylic acid dianhydride, and a (C6-C36) alicyclic tetracarboxylic acid dianhydride. In terms of having excellent yellowness even in a high temperature range, a (C8-C36) aromatic tetracarboxylic acid dianhydride is preferred. The number of carbon atoms in the tetracarboxylic acid dianhydride according to one embodiment of the present invention includes the number of carbon atoms contained in the carboxyl group. Preferably, the tetracarboxylic dianhydride according to one embodiment of the present invention is specifically 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2dicarboxylic anhydride, pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethylidene-4,4'-diphthalic dianhydride , 2,2-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, p-phenylenebis(trimellitate anhydride), thio- 4,4'-Diphthalic dianhydride, Sulfonyl-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, 1,4-Bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride Examples of the (C6-C50) aliphatic tetracarboxylic dianhydride include ethylene tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 3,4,9,10-perylene tetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, and 1,2,7,8-phenanthrene tetracarboxylic dianhydride. Specific examples of the (C6-C50) aliphatic tetracarboxylic dianhydride include ethylene tetracarboxylic dianhydride and 1,2,3,4-butane tetracarboxylic dianhydride. Examples of the (C6-C36) alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, 3,3',4,4'-bicyclohexyltetracarboxylic dianhydride, carbonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic) dianhydride, methylene-4,4'-bis(cyclohexane-1,2-dicarboxylic) dianhydride, carboxylic acid) dianhydride, 1,2-ethylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 2,2-propylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid dianhydride, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride, ethylene glycol-bis-(3,4-dicarboxylic acid anhydride phenyl) ether, etc.

[0079] For example, the acid dianhydride according to an embodiment of the present invention may be an acid dianhydride represented by the following Chemical Formula 3. By including a structural unit derived from the acid dianhydride represented by Chemical Formula 3, it is possible to achieve better chemical resistance, yellowness index, and the like.

[0080] [Chemical formula 3] [ka]

[0081] (In the above Chemical Formula 3, R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; p is an integer from 0 to 2.

[0082] In the chemical formula 3 according to one embodiment of the present invention, R 11 is (C1-C5) alkyl, or halo(C1-C5) alkyl; p may be an integer from 0 to 1, more preferably R 11 is (C1-C5) alkyl, or halo(C1-C5) alkyl; p may be 0.

[0083] The polyimide precursor according to one embodiment of the present invention may further include a unit structure derived from an acid dianhydride represented by the following Chemical Formula 3-1.

[0084] [Chemical formula 3-1] [ka]

[0085] (In the above chemical formula 3-1, D is a (C1-C10)alkylene unsubstituted or substituted with halo(C1-C10)alkyl; R 12 and R 13 are, independently of each other, (C1-C10) alkyl, or halo(C1-C10) alkyl; q and r are each independently an integer of 0 to 2.

[0086] For example, in Formula 3-1, D is (C1-C5) alkylene substituted or unsubstituted with halo(C1-C5) alkyl; R 12 and R 13 are, independently of each other, (C1-C5) alkyl; q and r may, independently of each other, be an integer from 0 to 1, specifically, D is a (C1-C3) alkylene substituted or unsubstituted with halo(C1-C3) alkyl; R 12 and R 13 are, independently of each other, (C1-C3) alkyl; q and r may, independently of each other, be an integer from 0 to 1, more specifically, D is a (C1-C3) alkylene substituted or unsubstituted with halo(C1-C3) alkyl; R 12 and R 13 are, independently of each other, (C1-C3) alkyl; q and r may be 0.

[0087] The polyimide precursor according to one embodiment of the present invention may include a repeating unit represented by the following Chemical Formula 11:

[0088] [Chemical formula 11] [ka]

[0089] (In the above Chemical Formula 11, A is O or S; R 1 and R 2are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; R a and R b are, independently of each other, hydrogen or (C1-C10) alkyl; m and n are, independently of each other, integers from 0 to 3; p is an integer from 0 to 2.

[0090] For example, in the above formula 11, A is O; 1 and R 2 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; R a and R b are, independently of each other, hydrogen or (C1-C10) alkyl; m and n are, independently of each other, an integer from 0 to 1; p may be an integer from 0 to 1, specifically, A is O; R 1 and R 2 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 11 is (C1-C5) alkyl, or halo(C1-C5) alkyl; R a and R b are, independently of each other, hydrogen, or (C1-C5) alkyl; m and n are, independently of each other, an integer from 0 to 1; p can be an integer from 0 to 1, more specifically, A is O; and m, n, and p can be 0.

[0091] A polyimide precursor according to one embodiment of the present invention may contain 10 to 100 mol %, specifically 30 to 100 mol %, preferably 40 to 95 mol %, and more specifically 50 to 80 mol % of the repeating unit represented by Chemical Formula 11.

[0092] The polyimide precursor according to one embodiment of the present invention may further include a repeating unit represented by the following formula 11-1.

[0093] [Chemical formula 11-1] [ka]

[0094] (In the above chemical formula 11-1, R 3 and R 4 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 5 is hydrogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; R a and R b are, independently of each other, hydrogen or (C1-C10) alkyl; s and t are, independently of each other, integers from 0 to 3; p is an integer from 0 to 2.

[0095] As an example, in the above-mentioned chemical formula 11-1, R 3 and R 4 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 is hydrogen, (C1-C10) alkyl, or halo(C1-C10) alkyl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; R a and R bare each independently hydrogen or (C1-C10) alkyl; s and t are each independently an integer of 0 to 3; p may be an integer of 0 to 2, and specifically, R 3 and R 4 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 is hydrogen, (C1-C5) alkyl, or halo(C1-C5) alkyl; R 11 is (C1-C5) alkyl, or halo(C1-C5) alkyl; R a and R b are, independently of each other, hydrogen or (C1-C5) alkyl; s and t are, independently of each other, an integer from 0 to 1; p may be an integer from 0 to 1, more specifically, R 11 is (C1-C5) alkyl; R a and R b are, independently of each other, hydrogen, or (C1-C5) alkyl; s, t, and p may be 0.

[0096] In one embodiment of the present invention, the repeating unit represented by Chemical Formula 11-1 may be contained in an amount of 10 to 90 mol %, specifically 30 to 80 mol %, more specifically 40 to 70 mol %, and even more specifically 50 to 60 mol %, based on the total mol % of the polyimide precursor.

[0097] The polyimide precursor according to one embodiment of the present invention may further include repeating units represented by the following chemical formulas 11-2 and 11-3.

[0098] [Chemical formula 11-2] [ka]

[0099] [Chemical formula 11-3] [ka]

[0100] (In the above chemical formulas 11-2 and 11-3, A is O or S; D is a (C1-C10)alkylene unsubstituted or substituted with halo(C1-C10)alkyl; R 1 ~R 4 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 5 is hydrogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 12 ~R 13 are, independently of each other, (C1-C10) alkyl, or halo(C1-C10) alkyl; R a and R b are, independently of each other, hydrogen or (C1-C10) alkyl; m and n are, independently of each other, integers from 0 to 3; q and r are, independently of each other, integers from 0 to 2; s and t are each independently an integer of 0 to 3.

[0101] As an example, in Formulas 11-2 and 11-3, A is O; D is (C1-C10) alkylene substituted or unsubstituted with halo(C1-C5) alkyl; R 1 ~R 4 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 is hydrogen or (C1-C10) alkyl; R 12 ~R 13 are, independently of each other, (C-C) alkyl, or halo(C-C) alkyl; R a and R b are, independently of each other, hydrogen, or (C1-C5) alkyl; m, n, q, r, s, and t may, independently of each other, be integers from 0 to 1.

[0102] In one embodiment of the present invention, the repeating unit represented by Chemical Formula 11-2 may be contained in an amount of 10 to 90 mol %, specifically 30 to 80 mol %, more specifically 40 to 70 mol %, and even more specifically 50 to 60 mol %, based on the total mol % of the polyimide precursor.

[0103] In one embodiment of the present invention, the repeating unit represented by Chemical Formula 11-3 may be contained in an amount of 10 to 50 mol %, specifically 30 to 50 mol %, more specifically 40 to 50 mol %, based on the total mol % of the polyimide precursor.

[0104] A polyimide precursor solution according to one embodiment of the present invention essentially contains a repeating unit represented by Chemical Formula 11 and may further contain a repeating unit represented by Chemical Formula 11-1; specifically, it may essentially contain a repeating unit represented by Chemical Formula 11 and may further contain a repeating unit represented by Chemical Formula 11-2; more specifically, it may essentially contain a repeating unit represented by Chemical Formula 11 and may further contain a repeating unit represented by Chemical Formula 11-1 and a repeating unit represented by Chemical Formula 11-2; even more specifically, it may essentially contain a repeating unit represented by Chemical Formula 11 and may further contain a repeating unit represented by Chemical Formula 11-1, a repeating unit represented by Chemical Formula 11-2, and a repeating unit represented by Chemical Formula 11-3.

[0105] A diamine compound according to a specific embodiment of the present invention may be prepared as shown in the following Reaction Scheme 1, but it goes without saying that it may be variously modified by a conventional organic synthesis method other than the following Reaction Scheme 1.

[0106] [Reaction Scheme 1] [ka]

[0107] (The definition of the substituent in Reaction Scheme 1 is the same as that of the substituent in Claim 1, and X is a halogen.)

[0108] Another aspect provides a polyimide precursor composition comprising a polyimide precursor and a solvent. The polyimide precursor composition according to one embodiment of the present invention contains the polyimide precursor of the present invention, and thus can realize a polyimide film having significantly improved optical and mechanical properties.

[0109] The polyimide precursor composition according to one embodiment of the present invention has high transparency and heat resistance, and does not increase the stress of the substrate even when subjected to high heat treatment, so that it can provide a polyimide film with excellent thermal dimensional stability, particularly a polyimide film with excellent transparency and a low coefficient of linear thermal expansion.

[0110] The polyimide precursor composition according to one embodiment of the present invention may be prepared using a polyimide precursor selected from the group consisting of ketones such as γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, and 4-hydroxy-4-methyl-2-pentanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers (cellosolves) such as ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, The solvent may be one or a mixture of two or more selected from acetates such as ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and dipropylene glycol monomethyl ether acetate; alcohols such as methanol, ethanol, propanol, ethylene glycol, propylene glycol, and carbitol; and amides such as N,N-dimethylpropionamide (DMPA), N,N-diethylpropionamide (DEPA), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N,N-dimethylformamide (DMF), N,N-diethylformamide (DEF), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), and N,N-dimethylmethoxyacetamide.

[0111] As an example, the organic solvent may be one or a mixture of two or more selected from the above-mentioned amides. For example, the organic solvent may have a boiling point of 300° C. or less. Specifically, for example, the organic solvent may be N,N-diethylformamide (DEF), N,N-diethylacetamide (DEAc), N-ethylpyrrolidone (NEP), N,N-dimethylpropionamide (DMPA), N,N-diethylpropionamide (DEPA), or a combination thereof.

[0112] The polyimide precursor composition according to one embodiment of the present invention may contain 10 to 13 wt % of the polyimide precursor containing the repeating unit represented by Chemical Formula 11 as a solid content, based on the total weight of the composition.

[0113] Specifically, the viscosity of a polyimide precursor composition according to one embodiment of the present invention may be 2,000 to 10,000 cps. Specifically, the viscosity may be 8,000 cps or less, more specifically, 7,000 cps or less. When the viscosity is within this range, the efficiency of degassing during processing of the polyimide film is excellent, providing process advantages. Therefore, it is preferable because a more uniform surface can be achieved. Here, the viscosity is measured using a Brookfield RVDV-III viscometer spindle No. 52 at room temperature (25°C), with a sample placed on the viscometer, at the point where the torque value reaches 80%, after stabilization for 2 minutes.

[0114] The polyimide precursor solution according to one embodiment of the present invention may be produced by polymerizing the diamine compound according to one embodiment of the present invention and the acid dianhydride in the presence of a solvent, and the molar ratio of the diamine compound according to one embodiment of the present invention to the acid dianhydride may be 2:1 to 1:2, or 1.5:1 to 1:1.5, or 1.1:1 to 1:1.1. The polymerization of the diamine compound and the acid dianhydride according to one embodiment of the present invention may be carried out at a temperature of 70°C or less, or 10 to 70°C, or 20 to 30°C.

[0115] In another aspect, there is provided a polyimide film prepared by imidizing the polyimide precursor according to one embodiment of the present invention or the polyimide precursor solution according to one embodiment of the present invention. For example, the imidization may be performed by chemical imidization or thermal imidization methods.

[0116] For example, the imidization may be performed by a thermal imidization method. When the imidization is performed by thermal imidization at a high temperature, more uniform mechanical properties can be imparted to the entire film. Specifically, the polyimide film according to the present invention may be produced by a production method including a step of applying the above-described polyimide precursor solution to a substrate and then performing a heat treatment.

[0117] In one embodiment of the present invention, the heat treatment may be carried out at a temperature of 500°C or less. Specifically, the heat treatment may include, but is not limited to, a first heat treatment step performed at 100°C or less, a second heat treatment step performed at a temperature above 100°C and 300°C or less, and a third heat treatment step performed at a temperature above 300°C and 500°C or less.

[0118] In one embodiment of the present invention, the substrate may be a glass substrate, a metal substrate, a plastic substrate, etc. Among them, a glass substrate is preferred because it has excellent thermal and chemical stability during the imidization and curing processes of the polyimide precursor solution and can be easily separated without damage from the polyimide film formed after curing without the need for a separate release agent treatment.

[0119] Specifically, in one embodiment of the present invention, the method for application is not particularly limited, but may be any one or more methods selected from spin coating, dipping, spraying, die coating, bar coating, roll coating, meniscus coating, flexographic printing, screen printing, bead coating, air knife coating, reverse roll coating, blade coating, casting coating, and gravure coating. In one embodiment of the present invention, after the heat treatment step, steps such as a drying step and a separation step from the substrate may be further included.

[0120] In an embodiment of the present invention, the molecular weight of the polyimide precursor including the repeating unit represented by Formula 11 is not particularly limited. For example, when the weight average molecular weight is in the range of 20,000 to 150,000 g / mol, more excellent physical properties can be obtained.

[0121] The polyimide precursor solution according to an embodiment of the present invention may further include additives such as a leveling agent, a flame retardant, an adhesion promoter, inorganic particles, an antioxidant, an ultraviolet inhibitor, and a plasticizer.

[0122] The present invention provides a polyimide film produced using the polyimide precursor composition of the present invention, and the polyimide film of the present invention may contain a repeating unit represented by the following Chemical Formula 12:

[0123] [Chemical formula 12] [ka]

[0124] (In the above chemical formula 12, A is O or S; R 1 and R 2 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; m and n are, independently of each other, integers from 0 to 2; p is an integer from 0 to 2.

[0125] For example, in Formula 12, A is O; R 1 and R2 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 11 is (C1-C10) alkyl; m and n are, independently of each other, integers from 0 to 1; p may be an integer from 0 to 1, specifically, A is O; R 1 and R 2 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 11 is (C1-C5) alkyl; m and n are, independently of each other, integers from 0 to 1; p may be an integer from 0 to 1, more specifically, A is O; R 1 and R 2 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 11 is (C1-C5) alkyl; m, n, and p may be 0.

[0126] The polyimide film according to one embodiment of the present invention may further include a repeating unit represented by the following Formula 12-1.

[0127] [Chemical formula 12-1] [ka]

[0128] (In the above chemical formula 112-1, A is O or S; D is a (C1-C10)alkylene unsubstituted or substituted with halo(C1-C10)alkyl; R 1 and R 2 are, independently of each other, halogen, C1-C10 alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 12 ~R 13 are, independently of each other, (C1-C10) alkyl, or halo(C1-C10) alkyl; m and n are, independently of each other, integers from 0 to 3; q and r are each independently an integer of 0 to 2.

[0129] As an example, in the above formula 12-1, A is O; D is (C1-C10) alkylene substituted or unsubstituted with halo(C1-C5) alkyl; R 1 ~R 2 are, independently of each other, halogen, (C1-C10) alkyl, or halo(C1-C10) alkyl; m, n, q, r, s, and t may, independently of each other, be integers from 0 to 1.

[0130] For example, the polyimide film according to an embodiment of the present invention may further include a repeating unit represented by the following Formula 13:

[0131] [Chemical formula 13] [ka]

[0132] (In the above Chemical Formula 13, R 3 and R 4 are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 5 is hydrogen, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; s and t are integers from 0 to 3; p is an integer from 0 to 2.

[0133] R according to one embodiment of the present invention 3 and R 4are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 is hydrogen, (C1-C10) alkyl, or halo(C1-C10) alkyl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; s and t are integers of 0 to 1; p may be an integer of 0 to 1, specifically, R 3 and R 4 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 is hydrogen, (C1-C5) alkyl, or halo(C1-C5) alkyl; R 11 is (C1-C5) alkyl, or halo(C1-C5) alkyl; s and t are integers from 0 to 1; p can be an integer from 0 to 1, more specifically, R 3 and R 4 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 is hydrogen, (C1-C10) alkyl, or halo(C1-C10) alkyl; R 11 is (C1-C10) alkyl, or halo(C1-C10) alkyl; s, t, and p may be 0.

[0134] For example, the polyimide film according to an embodiment of the present invention may further include a repeating unit represented by the following Formula 13-1:

[0135] [Chemical formula 13-1] [ka]

[0136] (In the above chemical formula 13-1, D is a (C1-C10)alkylene unsubstituted or substituted with halo(C1-C10)alkyl; R 3 ~R 4are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 5 is hydrogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R 12 ~R 13 are, independently of each other, (C1-C10) alkyl, or halo(C1-C10) alkyl; q and r are, independently of each other, integers from 0 to 2; s and t are each independently an integer of 0 to 3.

[0137] For example, in Formula 13-1, D is (C1-C10) alkylene substituted or unsubstituted with halo(C1-C5) alkyl; R 3 ~R 4 are, independently of each other, halogen, (C-C) alkyl, or halo(C-C) alkyl; R 5 is hydrogen or (C1-C10) alkyl; R 12 ~R 13 are, independently of each other, (C1-C5) alkyl, or halo(C1-C5) alkyl; q, r, s, and t may, independently of each other, be integers from 0 to 1.

[0138] For example, a polyimide film according to an embodiment of the present invention essentially includes a repeating unit represented by Chemical Formula 12 and may further include a repeating unit represented by Chemical Formula 12-1; specifically, it may essentially include a repeating unit represented by Chemical Formula 12 and further include a repeating unit represented by Chemical Formula 12-1 and a repeating unit represented by Chemical Formula 13; more specifically, it may essentially include a repeating unit represented by Chemical Formula 12 and further include a repeating unit represented by Chemical Formula 13 and a repeating unit represented by Chemical Formula 13-1; even more specifically, it may essentially include a repeating unit represented by Chemical Formula 12 and further include a repeating unit represented by Chemical Formula 12-1, a repeating unit represented by Chemical Formula 13, and a repeating unit represented by Chemical Formula 13-1.

[0139] The polyimide film according to one embodiment of the present invention has a low coefficient of thermal expansion and a low yellow index, is free from bending or flexing, and has excellent transparency and Young's modulus. The polyimide film according to one embodiment of the present invention may have a coefficient of thermal expansion (CTE) of 20 ppm / °C or less, for example, 15 ppm / °C or less, for example, 12 ppm / °C or less, for example, 10 ppm / °C or less, for example, 8 ppm / °C or less, for example, 7 ppm / °C or less, at 100 to 450°C, or may be, for example, more than -20 ppm / °C, for example, more than -10 ppm / °C, for example, more than -5 ppm / °C, or for example, more than 0 ppm / °C.

[0140] The polyimide film according to one embodiment of the present invention may have a YI according to ASTM E313 of less than 25, for example, 20 or less, for example, 16 or less, for example, 1 to 25, for example, 3 to 20, for example, 3 to 16.

[0141] The polyimide film according to one embodiment of the present invention may have a Young's modulus according to ASTM D882 of more than 6.0, for example more than 6.5, for example more than 6.0 to 8.5, for example more than 6.5 to less than 8.0.

[0142] As an example, a polyimide film according to one embodiment of the present invention may have a thermal expansion coefficient of 20 ppm / °C or less at 100 to 450°C, a YI according to ASTM E313 of less than 25, and a Young's modulus according to ASTM D882 of more than 6.0; for example, a thermal expansion coefficient of 15 ppm / °C or less at 100 to 450°C, a YI according to ASTM E313 of 20 or less, and a Young's modulus according to ASTM D882 of more than 6.5; for example, a thermal expansion coefficient of 12 ppm / °C or less at 100 to 450°C, a YI according to ASTM E313 of 16 or less, and a Young's modulus according to ASTM D882 of 6.8 or more.

[0143] For example, the polyimide film according to one embodiment of the present invention may have a thermal expansion coefficient of more than 0 to 20 ppm / °C at 100 to 450°C, a YI according to ASTM E313 of 1 to less than 25, and a Young's modulus according to ASTM D882 of more than 6.0 to 8.5; for example, the thermal expansion coefficient may be more than 0 to 15 ppm / °C at 100 to 450°C, a YI according to ASTM E313 of 3 to 20, and a Young's modulus according to ASTM D882 of more than 6.5 to 8.5; for example, the thermal expansion coefficient may be more than 0 to 12 ppm / °C at 100 to 450°C, a YI according to ASTM E313 of 3 to 16, and a Young's modulus according to ASTM D882 of 6.8 to less than 8.0.

[0144] The polyimide film according to one embodiment of the present invention may have a total light transmittance of 80% or more, for example, 85% or more. The polyimide film according to one embodiment of the present invention can have the above-described excellent optical and mechanical properties by being produced from a diamine compound having the above-described specific skeleton and a specific functional group, CF, introduced at a specific position.

[0145] Specifically, the polyimide film according to one embodiment of the present invention can provide a polyimide film with excellent optical properties, heat resistance, mechanical strength, and flexibility by including a repeating unit derived from the diamine compound represented by Chemical Formula 1. As a result, the polyimide film according to one embodiment of the present invention can be used in a variety of fields, such as device substrates, display cover substrates, optical films, integrated circuit (IC) packages, electrodeposited films, multilayer flexible printed circuits (FRCs), tapes, touch panels, and protective films for optical discs.

[0146] The weight-average molecular weight of the polyimide contained in the polyimide film according to one embodiment of the present invention may be 10,000 to 200,000 g / mol, or 20,000 to 100,000 g / mol, or 30,000 to 100,000 g / mol. The molecular weight distribution (Mw / Mn) of the polyimide may be in the range of 1.1 to 2.5. When the polyimide has the above-described weight-average molecular weight and molecular weight distribution, the polyimide film may exhibit more excellent properties, such as optical properties, heat resistance, mechanical strength, and flexibility.

[0147] The polyimide film according to one embodiment of the present invention may have a thickness of 5 to 15 μm. A polyimide film according to one embodiment of the present invention may have excellent heat resistance characteristics in response to temperature changes. Specifically, the polyimide film may have a thickness within the above range, and may undergo a first heating process at a temperature range of 100°C to 450°C at a heating rate of 5°C / min, followed by cooling at a temperature range of 400°C to 100°C at a cooling rate of 4°C / min. The thermal expansion change measured with a TMA (TMA450 manufactured by TA) may be 20 ppm / °C or less. Specifically, the coefficient of thermal expansion (CTE) may be 15 ppm / °C or less, more specifically, may be in the range of -20 to 10 ppm / °C.

[0148] A polyimide film according to an embodiment of the present invention can simultaneously satisfy excellent optical properties, heat resistance, mechanical strength, and flexibility due to the rigid structure derived from the diamine compound represented by Chemical Formula 1. In particular, the polyimide film not only exhibits excellent heat resistance against thermal shrinkage that may occur during high-temperature processes, but also exhibits excellent colorless and transparent optical properties, and can therefore be used in a variety of fields, such as device substrates, display substrates, optical films, integrated circuit (IC) packages, electrodeposited films, multilayer flexible printed circuits (FRCs), tapes, touch panels, and protective films for optical disks.

[0149] The polyimide film according to one embodiment of the present invention may be used as a laminate in the form of two or more layers laminated together. The present invention also provides an optoelectronic device and a flexible display including the above-mentioned polyimide film or a multilayer film including the polyimide film as a flexible substrate.

[0150] For example, the photoelectric element can be used in optical components, switches, optical modulators, etc., and is suitable for use as a highly heat-resistant substrate material that is required to have fine pattern forming properties. Examples of the flexible display include liquid crystal display devices (LCDs) and organic light emitting diodes (OLEDs), and are particularly suitable for OLED devices that use a low temperature polysilicon (LTPS) process that requires a high temperature process, but are not limited thereto.

[0151] The present invention will be described below with reference to specific examples and comparative examples. The following examples are provided to illustrate the technical concept of the present invention, and it will be apparent to those skilled in the art that the present invention is not limited to the following examples.

[0152] [Evaluation method] 1. Coefficient of linear thermal expansion (CTE) and glass transition temperature (Tg) The linear thermal expansion coefficient was measured by the TMA method using a TMA (TA Instrument, Discovery 450). The test piece size was 5 mm x 20 mm, the load was 0.02 N, and the heating rate was 5 °C / min. The CTE value was measured in the heating range of 100 °C to 450 °C. The Tg value was measured at the inflection point on the TMA graph in the temperature rising range from 100°C to 450°C.

[0153] 2.Yellowness (YI) In accordance with the ASTM E313 standard, measurements were made using a colorimeter (ColorQuest XE, manufactured by HunterLab) with a 10 μm thick polyimide film as a standard.

[0154] 3.Total light transmittance In accordance with the ASTM D1746 standard, the total light transmittance (unit: %) of a 10 μm thick polyimide film was measured over the entire wavelength range of 380 to 780 nm using a spectrophotometer (Shimadzu MPC-3100).

[0155] 4. Young's modulus According to ASTM D882, a polyimide film having a thickness of 10 μm, a length of 40 mm, and a width of 5 mm was measured at 25° C. and stretched at 10 mm / min using an Instron UTM 3365. The modulus unit is GPa.

[0156] 5. Thickness After coating PAA on 0.5T glass, the cured substrate was measured using a film thickness measuring instrument (Alpha step D500) manufactured by KLA Corporation. The unit is μm.

[0157] 6.Viscosity The value is measured using a Brookfield RVDV-III viscometer spindle No. 52 at room temperature (25°C) with a sample placed on it, and after the torque value reached 80%, the sample was left for 2 minutes to stabilize and then the value was measured. The unit is cps.

[0158] 7.Weight average molecular weight The film was dissolved in DMAc eluent containing 0.05 M LiBr. GPC was performed using a Waters GPC system, Waters 1515 isocratic HPLC pump, and Waters 2414 Reflective Index detector. Olexis, Polypore, and mixed D columns were connected, and polymethyl methacrylate (PMMA STD) was used as the standard. Analysis was performed at 35°C and a flow rate of 1 mL / min.

[0159] [Production Example 1] Production of diamine compound 1 [ka]

[0160] Step 1: Preparation of Compound A Under a nitrogen atmosphere, 4-nitro-2-trifluoromethylbenzoic acid (60 g) was added to 1 L of DCM and cooled to 0°C. Oxalic chloride (47 g) was slowly added and reacted for 1 hour, after which 2 g of DMF was added. After stirring at room temperature for 6 hours, the solvent was removed by distillation under reduced pressure, yielding 64 g of 4-nitro-2-trifluoromethylbenzoyl chloride. In a separate reactor, 39 g of 2-amino-4-nitrophenol and 7 g of TEA were dissolved in 390 mL of dioxane and cooled to 0°C. 64 g of the previously prepared benzoyl chloride was dissolved in 250 mL of dioxane and slowly added. The temperature was raised to room temperature, and after stirring for 12 hours, the solvent was removed by distillation under reduced pressure. The obtained solid was washed with 1N HCl and then filtered to obtain 72 g (yield 76%) of compound A (2-trifluoromethyl-N-(2-hydroxy-5-nitrophenyl)-4-nitrobenzamide) as a yellow solid.

[0161] Step 2: Preparation of Compound B 72 g of compound A (benzamide) prepared in step 1 was added to 72 g of 4-methylbenzenesulfonic acid and 750 mL of xylene, and the mixture was refluxed for 6 hours. After removing the solvent by distillation under reduced pressure, the mixture was precipitated with EtOH / HO (1:1) to obtain 51 g (74% yield) of compound B (5,4'-dinitro-2'-trifluoromethyl-2-phenylbenzoxazole).

[0162] Step 3: Preparation of diamine compound 1 Compound B obtained in Step 2 was dissolved in 500 mL of EtOH, and then 5 g of 10% PdC was added. After stirring for 6 hours with bubbling H2, the mixture was filtered to remove the catalyst and the solvent was removed by vacuum distillation. Recrystallization from EtOH yielded 33 g (78%) of pale brown diamine compound 1 (5,4'-diamino-2'-trifluoromethyl-2-phenylbenzoxazole).

[0163] 1H NMR (DMSO-d6, 500MHz, ppm): 7.82 (d, 1H, J=8.5Hz), 7.33 (d, 1H, J=8.5Hz), 7.06 (d, 1H, J=2 Hz), 6.882 (d, 1H, J=8.5Hz), 6.82 (d, 1H, J=2Hz), 6.63 (dd, 1H, J=8.5, 2Hz), 6.24 (s, NH2), 5.04 (Br, NH2).

[0164] [Production Example 2] Production of diamine compound 2 [ka] It was prepared as described in Polymer 49 (2008) 2644-2649.

[0165] Preparation of polyimide precursor solution [Example 1] PMDA / diamine compound 1 (molar ratio 1 / 0.999) After 184 g of N,N-dimethylpropionamide (DMPA) was charged into a stirrer under a nitrogen stream, 20.13 g of a diamine compound (Compound 1) was dissolved in the reactor while maintaining the reactor temperature at 25°C. 15.00 g of PMDA (pyromellitic dianhydride) was added to the diamine solution of Formula 1 at the same temperature and stirred for a certain period of time while dissolving. DMPA was added to prepare a polyimide precursor solution with a solids concentration of 10.5 wt%. The viscosity of the polyimide precursor solution was 4100 cps. Furthermore, the molecular weight of the solution was measured and found to be 91,000 g / mol.

[0166] [Example 2] 6FDA / PMDA / Compound 1 / TFMB (molar ratio: 0.3 / 0.7 / 0.5 / 0.5) 203 g of N,N-dimethylpropionamide (DMPA) was charged into a stirrer under a nitrogen stream. While maintaining the reactor temperature at 25°C, 10.48 g of TFMB (2,2'-bis(trifluoromethyl)-4,4'-biphenyldiamine) and 9.59 g of Compound 1 were dissolved. 8.72 g of 6FDA (4,4'-(hexafluoroisopropylidene)diphthalic anhydride) and 10 g of PMDA (pyromellitic dianhydride) were added to the TFMB / Compound 1 solution at the same temperature and stirred for a period of time while dissolving. DMPA was added to the resulting polyimide precursor solution to achieve a solids concentration of 10.4 wt%. The viscosity of the polyimide precursor solution was 4500 cps. The molecular weight of the solution was measured to be 95,000 g / mol.

[0167] [Example 3] 6FDA / PMDA / Compound 2 / Compound 1 (molar ratio: 0.35 / 0.65 / 0.5 / 0.5) 218.5 g of N,N-dimethylpropionamide (DMPA) was charged into a stirrer under a nitrogen stream, and 10.3 g of compound 2 and 10.33 g of compound 1 were dissolved in the reactor while maintaining the reactor temperature at 25°C. 10.96 g of 6FDA (4,4'-(hexafluoroisopropylidene)diphthalic anhydride) and 10 g of PMDA (pyromellitic dianhydride) were added to the compound 2 / compound 1 solution at the same temperature and stirred for a certain period of time while dissolving. DMPA was added to the polyimide precursor solution to adjust the solids concentration to 10.2 wt%. The viscosity of the polyimide precursor solution was 4300 cps. The molecular weight of the solution was measured to be 89,000 g / mol.

[0168] [Comparative Example 1] PMDA / 2,5-diaminobenzoxazole (molar ratio: 1 / 0.999) After 161 g of N,N-dimethylpropionamide (DMPA) was charged into a stirrer under a nitrogen stream, 15.66 g of 2,5-diaminobenzoxazole was dissolved in the reactor while maintaining the reactor temperature at 25°C. 15 g of PMDA (pyromellitic dianhydride) was added to the 2,5-diaminobenzoxazole solution at the same temperature and stirred for a certain period of time while dissolving. DMPA was added to prepare a polyimide precursor solution with a solids concentration of 9.3 wt%. The viscosity of the polyimide precursor solution was 4800 cps. The molecular weight of the solution was measured to be 93,000 g / mol.

[0169] Comparative Example 2 PMDA / 1H-benzimidazole-2,5-diamine (molar ratio: 1 / 0.999) After 159 g of N,N-dimethylpropionamide (DMPA) was charged into a stirrer under a nitrogen stream, 15.40 g of 1H-benzimidazole-2,5-diamine was dissolved in the reactor while maintaining the reactor temperature at 25°C. 15 g of PMDA (pyromellitic dianhydride) was added to the 1H-benzimidazole-2,5-diamine solution at the same temperature and stirred for a certain period of time while dissolving. DMPA was added to prepare a polyimide precursor solution with a solids concentration of 9.1 wt%. The viscosity of the polyimide precursor solution was 5100 cps. The molecular weight of the solution was measured to be 105,000 g / mol.

[0170] Comparative Example 3 PMDA / Compound 2 (molar ratio: 1 / 0.999) After 184.2 g of N,N-dimethylpropionamide (DMPA) was charged into a stirrer under a nitrogen stream, 20.07 g of a diamine compound (Compound 2) was dissolved in the solution while maintaining the reactor temperature at 25°C. 15 g of PMDA (pyromellitic dianhydride) was added to the solution at the same temperature and stirred for a certain period of time while dissolving. DMPA was added to prepare a polyimide precursor solution with a solids concentration of 10.4 wt%. The viscosity of the polyimide precursor solution was 4300 cps. The molecular weight of the solution was measured to be 95,000 g / mol.

[0171] Comparative Example 4 6FDA / PMDA / Compound 2 / TFMB (molar ratio: 0.3 / 0.7 / 0.5 / 0.5) 203 g of N,N-dimethylpropionamide (DMPA) was charged into a stirrer under a nitrogen stream. 10.48 g of TFMB (2,2'-bis(trifluoromethyl)-4,4'-biphenyldiamine) and 9.57 g of Compound 2 were dissolved in the reactor while maintaining the reactor temperature at 25°C. 8.72 g of 6FDA (4,4'-(hexafluoroisopropylidene)diphthalic anhydride) and 10 g of PMDA (pyromellitic dianhydride) were added to the TFMB / Compound 2 solution at the same temperature and stirred for a period of time while dissolving. DMPA was added to the resulting polyimide precursor solution to achieve a solids concentration of 10.6 wt%. The viscosity of the polyimide precursor solution was 4600 cps. The molecular weight of the solution was measured to be 93,000 g / mol.

[0172] Polyimide film manufacturing The polyimide precursor solutions prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were spin-coated onto glass substrates to a thickness of 10 μm. The glass substrates coated with the polyimide precursor solutions were placed in an oven and heated at a rate of 4°C / min, followed by curing at 80°C for 30 minutes, 220°C for 30 minutes, and 450°C for 1 hour. After the curing process was completed, the glass substrates were immersed in water to peel off the films formed on the glass substrates, and the films were dried in an oven at 100°C to produce polyimide films.

[0173] The physical properties of the polyimide film produced by the above method were measured by the above evaluation methods and are shown in Table 1 below.

[0174] [Table 1]

[0175] As shown in Table 1, the polyimide films prepared from the polyimide precursor solutions of Examples 1 to 3 containing the structural unit derived from the diamine compound represented by Chemical Formula 1 have a thermal expansion coefficient of 0 to 15 ppm / °C, a total light transmittance of 80% or more, a yellowness index of less than 25, and a Young's modulus of 6.0 GPa or more, and are therefore confirmed to exhibit mechanical and optical properties suitable for application to flexible display panels.

[0176] In particular, the polyimide film prepared from the polyimide precursor solution of Example 3 contains a combination of structural units derived from a diamine compound exhibiting a negative thermal expansion coefficient and structural units derived from a diamine compound exhibiting a positive thermal expansion coefficient. This results in a thermal expansion coefficient of 5.7 ppm / °C, which is very close to 0, and thus it can be confirmed that the polyimide film is further advantageous for high-temperature processes of low-temperature polysilicon TFTs (LTPS TFTs).

[0177] Therefore, the polyimide precursor according to one embodiment of the present invention can be used to produce a polyimide film that simultaneously satisfies high heat resistance, excellent optical and mechanical properties such as a coefficient of thermal expansion, yellowness index, and Young's modulus.

[0178] Although the present invention has been described above using specific details and limited embodiments, this is merely provided for a more general understanding of the present invention, and the present invention is not limited to the above embodiments. Those skilled in the art will appreciate that various modifications and variations can be made from such descriptions.

[0179] Therefore, the spirit of the present invention should not be limited to the described embodiments, and not only the scope of the attached claims, but also anything that has equivalent or equivalent modifications to the scope of these claims can be said to fall within the scope of the spirit of the present invention.

Claims

1. A polyimide precursor comprising a structural unit derived from an acid dianhydride represented by the following chemical formula 3 and a structural unit derived from a diamine compound represented by the following chemical formula 1: [Chemical formula 1] 【Chemistry 1】 In the above Chemical Formula 1, A is O or S; R １ and R ２ are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; m and n are each independently an integer from 0 to 3; [Chemical formula 3] 【Chemistry 2】 In the above Chemical Formula 3, R 11 is (C1-C10) alkyl or halo(C1-C10) alkyl; p is an integer of 0 to 2.

2. In the above Chemical Formula 1, R １ and R ２ are, independently of each other, halogen, (C1-C10) alkyl, or halo(C1-C10) alkyl; 2. The polyimide precursor according to claim 1, wherein n and m are each independently an integer of 0 to 1.

3. The polyimide precursor according to claim 1 , wherein the formula 1 is represented by the following formula 2: [Chemical formula 2] 【Transformation 3】 In the above Chemical Formula 2, R １ and R ２ are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; m and n are each independently an integer of 0 to 3;

4. In the above chemical formula 2, R １ and R ２ are each independently a halogen, a (C1-C5) alkyl, or a halo(C1-C5) alkyl; and n and m are each independently an integer from 0 to 1.

5. The polyimide precursor according to claim 1 , further comprising a structural unit derived from a diamine compound represented by the following chemical formula 4: [Chemical formula 4] 【Chemistry 4】 In the above Chemical Formula 4, R ３ and R ４ are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R ５ is hydrogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; s and t are integers of 0 to 3.

6. The polyimide precursor according to claim 1 , comprising a repeating unit represented by the following chemical formula 11: [Chemical formula 11] 【Transformation 5】 In the above Chemical Formula 11, A is O or S; R １ and R ２ are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R １１ is (C1-C10) alkyl, or halo(C1-C10) alkyl; R ａ and R ｂ are, independently of each other, hydrogen or (C1-C10) alkyl; m and n are each independently an integer from 0 to 3; p is an integer of 0 to 2.

7. 7. The polyimide precursor according to claim 6, comprising 10 to 100 mol % of the repeating unit represented by Chemical Formula 11.

8. A polyimide precursor solution comprising the polyimide precursor according to claim 1 and a solvent.

9. The polyimide precursor solution according to claim 8 , wherein the solvent is selected from amides.

10. 10. The polyimide precursor solution according to claim 9, wherein the amide is N,N-diethylacetamide, N,N-diethylformamide, N-ethylpyrrolidone, N,N-dimethylpropionamide, N,N-diethylpropionamide, or a mixture thereof.

11. A polyimide film comprising a repeating unit represented by the following chemical formula 12: [Chemical formula 12] 【Transformation 6】 In the above chemical formula 12, A is O or S; R １ and R ２ are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R １１ is (C1-C10) alkyl, or halo(C1-C10) alkyl; m and n are each independently an integer from 0 to 2; p is an integer of 0 to 2.

12. The polyimide film according to claim 11, further comprising a repeating unit represented by the following formula 13: [Chemical formula 13] 【Transformation 7】 In the above Chemical Formula 13, R ３ and R ４ are, independently of each other, halogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R ５ is hydrogen, (C1-C10)alkyl, halo(C1-C10)alkyl, (C1-C10)alkoxy, or (C6-C12)aryl; R １１ is (C1-C10) alkyl, or halo(C1-C10) alkyl; s and t are integers from 0 to 3; p is an integer of 0 to 2.

13. The polyimide film according to claim 11, having a thermal expansion coefficient of more than 0 to 20 ppm / °C at 100 to 450°C.

14. YI according to ASTM E313 is less than 25, 12. The polyimide film according to claim 11, having a Young's modulus according to ASTM D882 of greater than 6.

0.

15. The polyimide film according to claim 11, which is used for a substrate for devices, a substrate for displays, an optical film, an IC package, an electrodeposited film, a multilayer FRC, a tape, a touch panel, or a protective film for an optical disk.

16. A photoelectric device comprising the polyimide film of claim 11.

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